Display screen or portion thereof with transitional graphical user interface



FIG. 1 is the first image in a sequence for a display screen or portionthereof with transitional graphical user interface showing our newdesign;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 is the fourth image thereof;

FIG. 5 is the fifth image thereof; and,

FIG. 6 is the sixth image thereof.

The outermost broken lines in the figures show the display screen orportion thereof and form no part of the claimed design. The remainingbroken lines depict portions of the graphical user interface that formno part of the claimed design.

The appearance of the transitional graphical user interface sequentiallytransitions between the images shown in FIGS. 1 through 6. The processor period in which one image transitions to another forms no part of theclaimed design.

CLAIM We claim the ornamental design for a display screen or portionthereof with transitional graphical user interface, as shown anddescribed.